Hydraulic weight control and compen-sating apparatus for subsurface well bore devices



y 1960 A. w. KAMMERER, JR 2,945,676

HYDRAULIC WEIGHT CONTROL AND COMPENSATING APPARATUS FOR SUBSURF'ACE WELLBORE DEVICES Filed Nov. 8, 1956 ORIFICE Ezsze va/e 1.

INVENTOR. flea/ale 7V. MA /[1e52, Jie.

Kathi-iii Patented July 19, 1960 HYDRAULIC WEIGHT CQNTROL AND COMPEN-SATING APPARATUS FOR SUBSURFACE WELL BORE DEVICES Archer W. Kammerer,Jr., Fullerton, Califl, assignor of three-fifths to Archer W. Kammererand one-fifth to Jean K. Lamphere, both of Fullerton, Calif.

Filed Nov. 8, 1956, Ser. No. 621,158

4 Claims. (Cl. 255-19) The present invention relates to apparatusparticularly useful in the drilling, completion and production of wells.

An object of the present invention is to provide improved apparatuscapable of maintaining a substantially uniform or constant tension in arunning-in string, such as drill pipe, drill casing or tubing, disposedin a well bore and usually operatively connected to a device in the wellbore, such as a drill bit or milling tool.

Another object of the invention is to provide an apparatus capable ofmaintaining a substantially constant weight on a drill bit, millingcutter, and the like, disposed in a well bore.

A further object of the invention is to provide an apparatus formaintaining a substantially constant weight on a drill bit, millingcutter, and the like, despite vertical movement of the dnillingequipment at the top of the well bore, such as occurs when the drillingequipment is mounted on a floating barge.

An additional object of the invention is to provide an apparatus formaintaining a substantially constant tension in a running-in stringdisposed in a well bore, in which the tension can be readily changed,whenever desired, in

a simple manner.

Yet another object of the invention is to provide apparatus formaintaining a substantially constant tension in a runningin stringdisposed in a well bore, the apparatus being located above the top ofthe well bore, thereby avoiding design limitations which would beimposed in the event it were necessary to locate the apparatus in thewell bore, which is usually of relatively small diameter.

Still a further object of the invention is to provide a hydraulicallyoperated apparatus for maintaining a substantially constant tension in arunningdn string disposed in a well bore, the tension being readilychanged by the expedient of altering the hydraulic, pressure in theapparatus.

Another object of the invention is to provide an apparatus formaintaining a substantially constant weight on a drill bit, millingcutter, and the like, which also indicates the extent of footage drilledor milled away by the bit or cutter.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification.

It will now be described in detail, for the purpose of illustrating thegeneral principles of the invention; but it is to be understood thatsuch detailed description is not to 'be taken in a limiting sense, sincethe scope of the invention is best defined by the appended claims.

Referring to the drawings: Figure l is a diagrammatic view of oneapplication of the invention;

Fig. 2 is a diagrammatic view of the weight control and compensatingapparatus forming part of the equipment illustrated in Fig. l.

The weight controland compensating apparatus A is disclosed in thedrawings as being applied to the drilling of a well bore B. It islocated between the traveling block 'C of a drilling rig, which may bemounted on land or on a floating barge D appropriately anchored inplace. The traveling block is associated with the usual lines E passingover the crown block F at the upper end of the derrick G secured inplace on the floating barge shown. The lower portion of the weightcontrol apparatus .A may be secured to a swivel H, of any desired type,which is, in turn, connected to a string of drill pipe I, the upperportion of which is usually a Kelly or grief stern slidably splined tothe rotary table L of the apparatus for rotating the drill stem, inorder to rotate the drill bit M connected to the lower end of thelatter. As is usual in the rotary drilling of well bores, suitabledrilling fluid is pumped down the string of drill pipe I and will exitfrom the drill bit M, carrying the cuttings upwardly out of the hole B.

in lieu of drill pipe, other drill stnings I may be used, such as drillcasing or even tubing. Moreover, in lieu of a rotary drill bit M fordrilling'the hole, the drill string may be connected to a milling tool,or the like, which is used for milling away metallic and other devicesin the well bore, casing sections, etc.

The weight control and compensating apparatus A is showndiagrammatically in Fig. 2. it includes a cylinder 10 of the requiredlength and cross-sectional area having an upper cylinder head 11 and alower cylinder head 12. The lower cylinder head is provided with asuitable connection 13, such as an eye, by virtue of which it isattached to the upper portion of the rotary swivel H. A piston 14 isreciprocably mounted in the cylinder 10, the piston being secured to apiston rod 15 extending upwardly through the upper cylinder head 11,this rod having a suitable eye or bail 16 at its upper end to receivethe hook 17 of the traveling block C. For the purpose of preventingleakage from the cylinder, a rod packing 18 is provided in the uppercylinder head 11 to slidably and sealingly engage the piston rod 15.Leakage around the piston 14 is prevented by a suitable packing or sealring device 19 mounted in a piston groove 2% and sealingly engaging thewall of the cylinder 10.

The cylinder is filled with a suitable liquid, such as oil, completelybetween the piston 14 and the upper cylinder head 11. The liquid isderived from a suitable reservoir 21 that is connected to a motor drivenpump 2'2, preferably of a high pressure centrifugal type, the liquiddischarging from the pump through an inlet line 2 3 opening into theupper portion 24 of the cylinder 10. An outlet line 25 is also connectedto the upper portion of the cylinder, this outlet line returning theliquid to the reservoir 21. The outlet line includes a choke orifice 26to enable a back pressure to be built up in the inlet line 23 andcylinder 24 above the piston 14, so that liquid under a desired pressureis contained in the cylinder space 24 to enable the cylinder lit to besupported by the piston 14 through the liquid medium. 7

The weight control and compensating apparatus A is a telescopic jointfor supporting a portion of the weight of the running-in string or drillstring 1. Thus, the drill string is suspended from the swivel H, theswivel, in turn, being carried by the cylinder 16', the load beingtransferred from the cylinder head 11 through the liquid medium in thecylinder space 24 to the piston 14 and the piston rod 15, and from thelatter to the traveling block C and the usual lines E connected in aknown manner to the drawworks (not shown). The pressure of the liquid inthe cylinder space 24 will determine the lifting force on its cylinderhead 11 and on the drill string I depending from and connected to thecylinder. The greater the pressure, the greater will be the liftingforce; whereas, contrariwise, the lesser the pressure, the less will bethe lifting force. Thus, by controlling the liquid pressure in thecylinder space 24, the net weight of the string of drill pipe J imposedon the dnill bit M to force it against the bottom of the well bore B canbe regulated, and this netweight, is maintained constant provided thepressure of the liquid in the cylinder space 24- is maintained constant.

By way of example, if the internal diameter of the cylinder is madeabout one foot, its cross-sectional area above the piston will be aboutone hundred square inches, neglecting the area of the piston rod. If itis assumed that the drill string J has a total weight when in the wellbore of about 90,000 lbs., and if the drilling weight on the drill bit Mis to be 10,000 lbs., then a pressure of about 800 p.s.i. in the liquidin the. cylinder space 24 will result in a supporting force on the drillstring J in an upward direction of 80,000 lbs., leaving a net of 10,000lbs. imposed on the drill bit. If this pressure is maintained in thecylinder space, the drilling weight on the drill bit M will remain atthe constant value of 10,000 lbs., provided, of course, that thecylinder connected to the drill string I does not lower sufiiciently asdrilling proceeds to bring the upper cylinder head 11 into contact withthe piston 14. Before this occurs, the drawworks will be suitablymanipulated so as to lower the piston 14 within the cylinder 10 to theproper extent. By way of example, the cylinder may be five to ten feetin length, allowing approximately that much relative downward movementof the cylinder 10' in the drill string with respect to the piston 14without any necessity for operating the dravwvorks and the lines E andtraveling block C connected thereto. So long as the pressure in thecylinder space 24 is maintained at the required value, a constantdrilling weight will be imposed on the bit M. Moreover, as the cylinder10 moves downwardly along :the rod 15, an indication of the footagebeing drilled is imparted to the operator at the top of the well bore byobservation of the relative position of'the cylinder along the rod.

The centrifugal pump 22 is operating constantly to force fiuid into thecylinder 10, a back pressure being built up in the cylinder by virtue ofthe throttling action of the choke orifice 26, which, however, allowsliquid pumped into the cylinder space 24 to return through the exhaustline 25 to the reservoir 21. The pressure in the cylinder can beascertained by means of a suitable pressure gauge 30 that may beconnected anywhere in the inlet line 23. By varying the speed of thepump 22, the pressure can be changed to the desired value. Another wayof altering the pressure is to provide a variable choke orifice 26. Inany event, the pressure can be maintained at the desired value in thecylinder space 24 for the purpose of hydraulically supporting thedesired portion of the 'weightof the drill string J, leaving the balanceof the weight available for imposition on the drill bit M to penetrateits cutters into the bottom of the well bore B.

The apparatus A will maintain a constant drilling weight when used underconditions in which the derrick G may partake of some vertical movement,as is associated with the mounting of the derrick on a floating barge Dthat may be anchored against lateral displacement, but which will stillpartake of up and down movement under the action of ocean waves, and thelike. A direct con nection between the traveling block C and the swivelH would cause alternate raising and lowering of the entire drill stringJ, varying the drilling weight of the bit M against the bottom of thewell bore, either reducing the drilling weight considerably or imposingtoo heavy a drilling Weight thereon. In fact, that drill bit could belifted completely off the bottom of the hole as the barge D rises, andan excess of drilling weight might be imposed on the drill bit as thebarge descends.

The apparatus disclosed. permits lowering and elevation. of therbargeD-without correspondingly lowering and elevating the drill string J,since the apparatus A embodies a telescopic joint in the form of thepiston 14 and piston rod 15, on the one hand, and the cylinder 10, onthe other hand. Thus, as the barge D and derrick G move upwardly, thepiston 14 will be moved upwardly therewith with respect to the cylinder10; whereas, downward movement of the barge D. and derrick G results ina downward movement of the piston 14 withrespect to the: cylinder :10.Despite such upward and. downward movements, the cylinder 10 does notmove vertically to any significant extent, and the pressure in thecylinder space 24' can still be maintained substantially constant, sothat aconstant elevating force by the liquid in the cylinder ismaintained thereon, to insure the same net downward drilling weight of.the rotary drill bit M against the bottom of the hole.

Assuming that the barge D rises, to shift the piston rod 15 and piston14 in an upward direction within the cylinder 10, the liquid pressure inthe cylinder space 24 would tend to increase, but the excess pressure ispromptly and rapidly dissipated by being forced through the chokeorifice 26, returning to the reservoir 21. On the other hand, should thebarge D descend, the piston rod 15 and the piston 14 connected theretowould also lower in the cylinder 10. However, the centrifugal pump 22 isoperating at a sufiicient volumetric rate as to supply the requiredadded volume of liquid to the cylinder space 24 promptly and rapidly.Under these conditions, a lesser amount of liquid will pass through thechoke orifice 26', the pressure in the cylinder, at best, only droppingmomentarily and then ,being built up to the required value. Thus, theupward and downward movements of the barge D under wave action are nottransmitted to the drill string J, the piston 14 merely constantlytelescoping within the cylinder, with the cylinder liquid thereabovebeing maintained at a substantially constant pressure, to retain thedesired upward supporting force on the drill string J, which results inthe appropriate down weight on the rotary drill bit M against the'bottom of the hole B being produced.

As disclosed in Fig. l of the drawings, the well bore B is being drilledin the bottom or floor of the ocean N under such conditions that it maybe desired to use drill casing instead of a drill pipe to rotate therotary drill bit M. When the hole is completed, the casing need not bepulled from the well bore B, but can be cemented in place. Regardless ofthe use of drill pipe, drill casing, or any other string of tubing, thecompensating device A will still function to insure a substantiallyconstant applic-ation of drilling weight on the bit, As drilling pro,-gress proceeds, the gradual lowering of the cylinder head 11 along thepiston rod 15 will indicate to the operator at the top of the hole theextent of footage that is being made.

If desired, the cylinder space 31 on the low pressure side of the piston14 may be sealed off, containing air at atmospheric pressure that wouldbe compressed sl ghtly during downward movement of the piston 14 in thecyhnder. However, to insure that any liquid in the cylinder above thepiston 14 which might leak by the piston will not fill the cylinderspace 31, a suitable drain hole 32 may be provided in the lower cylinderhead 12 through which the leakage can be dissipated.

Although the invention has been described particularly with respect tothe drilling of a well bore B, or the mill ng of equipment in the wellbore, it can. be used for maintaining a constant desirable drillingweight on any type of running-in string, such as a tubular string thatis to be maintained in tension in a well bore. It is merely necessary toprovide the proper desired liquid pressure in the cylinder 10 andmaintain such pressure constant to insure the maintenance of a constanttension in the tubular string J. In. order to supply therequired tensionthroughout the entire length of the tubing string, the pressure, in thecylinder space 24 would be sutficient to more, than overcome the deadweight of the tubular string.

The inventor claims:

1. In an apparatus for maintaining a predetermined stress in arunning-in string disposed in a well bore which is supported by a rigincluding a suspension mechanism: elongate cylinder means; piston meansslidable in said cylinder means; one of said means having a devicethereon for operative connection to the running-in string; the other ofsaid means having a device thereon for operative connection to thesuspension mechanism, whereby said cylinder means and piston means aredisposed between the suspension mechanism and running-in string; meansfor constantly feeding fiuid under pressure to said cylinder means,whereby the stress of the running-in string and of said one means istransmitted through the fluid to said other means and suspensionmechanism; and means for constantly conducting such fluid from saidcylinder means, said conducting means including flow restrictinginstrumentalities for creating a back pressure in the fluid in saidcylinder means.

2. In an apparatus for maintaining a predetermined stress in arunning-in string disposed in a well bore which is supported by a rigincluding a suspension mechanism: elongate cylinder means; piston meansslidable in said cylinder means; one of said means having a devicethereon for operative connection to the running-in string; the other ofsaid means having a device thereon for operative connection to thesuspension mechanism, whereby said cylinder means and piston means aredisposed between the suspension mechanism and running-in string; meansfor constantly feeding fluid under pressure to said cylinder means,whereby the stress of the running-in string and of said one means istransmitted through the fluid to said other means and suspensionmechanism; and means for constantly conducting such fluid from saidcylinder means,

said conducting means including a flow restricting orifice for creatinga back pressure in the fluid in said cylinder means.

3. In an apparatus for maintaining a predetermined stress in arunning-in string disposed in a well bore which is supported by a rigincluding a suspension mechanism: elongate cylinder means; piston meansslidable in said cylinder means; one of said means having a devicethereon for operative connection to the running-in string; the other ofsaid means having a device thereon for operative connection to thesuspension mechanism, whereby said cylinder means and piston means aredisposed between the suspension mechanism and running-in string; asource of fluid; a pump connected to said source and cylinder means forconstantly forcing fluid under pressure into said cylinder means;whereby the stress of the running-in string and said one means istransmitted through the fluid to said other means and suspensionmechanism; and means for constantly conducting such fluid from saidcylinder means to said source, including flow restrictinginstrumentalities for creating a back pressure in the fluid in saidcylinder means.

4. In an apparatus for maintaining a predetermined stress in arunning-in string disposed in a well bore which is supported by a rigincluding a suspension mechanism: elongate cylinder means; piston meansslidable in said cylinder means; one of said means having a devicethereon for operative connection to the running-in string; the other ofsaid means having a device thereon for operative connection to thesuspension mechanism, whereby said cylinder means and piston means aredisposed between the suspension mechanism ad running-in string; a sourceof fluid; a pump connected to said source and cylinder means forconstantly forcing fluid under pressure into said cylinder means,whereby the stress of the running-in string and said one means istransmitted through the fluid to said other means and suspensionmechanism; and means for constantly conducting such fluid from saidcylinder means to said source, including a flow restricting orifice forcreating a back pressure in the fluid in said cylinder means.

References Cited in the file of this patent UNITED STATES PATENTS839,656 Sharp Dec. 25, 1906 1,311,108 Beckwith July 22, 1919 1,938,690Burmist Dec. 12, 1933 2,109,297 McMurry et al Feb. 22, 1938 2,225,515Wood Dec. 17, 1940 2,259,019 Carr et al Oct. 14, 1941 2,353,293 BrookingJuly 11, 1944 2,497,083 Hildebrand Feb. 14, 1950 2,712,932 Gould July12, 1955 2,772,085 Dodge Nov. 27, 1956 FOREIGN PATENTS 77,087Netherlands Jan. 15, 1955

